Electrical coil



March 19, 1940. w PAGENKOPF 2,193,980

ELECTRICALCOIL Filed Sept. 16, 1937 INVENTOR.

WALTER H. PAGENKOPF Patented Mar. 19, 1940 UNITED ,STATES ELECTRICAL COIL Walter H. Pagenkopf, La Grange, 111., assignmto Teletype Corporation, Chicago, 111., a corporation of Delaware Application September: 16, 1937, Serial No. 164,148

2 Claims.

The present invention relates to methods of and accessories for winding electrical coils and particularly to a method and instrumentality for securing and lashing the final convolution of an electrical magnet or solenoid winding.

The main object of the present invention is to provide means for securing the last turn of an electrical coil so as to prevent its becoming shortcircuited while afiording a lasting anchorage means preparatory to the application of the outer coil wrapping.

Another object of the invention is to produce a back-lashing convolution of uninsulated wirewithout hazarding the adjacent convolutions to the possibilities of short circuiting or without hav- I ing to provide upon the back-lashing convolution the special precautions of insulation sheathing to prevent short-circuiting of adjacent convolutions.

Electromagnets and other coil assemblies adapted to certain manufacturing practices are frequently terminated with stranded or woven wire leads which are soldered to the'wire that comprises the major coil winding. Wire terminals of this type extend from the coil to be attached to a circuit and for securement they are covered with a sleeve of insulating material, doubled back, and back-lashed against unraveling. The present invention concerns itself with an improved method of securing the terminal convolutions of a coil having the features of economical construction, low manufacturing cost, but most important that of effecting a positive lashing means for the coil winding, which may thereafter be covered by the finish wrapper without presenting a bulge or protuberance but maintaining a smooth cylindrical contour of the coil.

This feature is particularly adapted to the socalled solderless lead type of coil winding. Its utility is of paramount importance to coils of this type because the lashing plate provides not only a means for anchoring the final convolutions against unraveling, but also, in cooperation with the wrapping, contributes appreciably towards relieving any strains which might be transmitted on through the solder connection between the coil wire of which windings of this type are conventionally made, and the stranded or woven wire throughpanying drawing is a perspective view of a cylindrical type magnet, a portion of whose finish wrapper has been torn away to reveal the disposition of the lashing plate and its adjacent convolutions.

A magnet winding is represented by the general character ll comprising a soft iron core 12, the flanges I3 and M which together with an intermediate sleeve form the spool, and a plurality of superimposedlayers of winding 15. The inner winding terminal lead may protrude from the assembly in any suitable mannerand may be secured against unraveling by the superimposed lappings of wire l5. In the single figure of the drawing there is no specific illustration of the inner terminal since the improvement concerns primarily a manner of securing outer coil terminals. Nevertheless, it will be understood that the novel principles disclosed herein may have application elsewhere as well, such as, for example,

in connection with inner coil terminals or intermediate coil terminals. The final or outer terminal lead which is improved in accordance with the teachings herewith proposed has secured to it a length of flexible wire preferably of the stranded type, indicated 11, which is left bare or with but its ordinary insulating coat of enamel. In the particular illustration, the principal winding 35,"

as viewed from the foremost end of the coil, has

. been applied in a clockwise direction. .The final in an opposite direction from the principal con-' volution l5.

The lashing plate 2i may be made of thin fiber or other suitable insulation material. Its proportions may vary in accordance with the particular type of wire and size of coil. A secondary eyelet 22 formed in the opposite end of lashing plate 2! receives the approaching portion of the reversed loop which has been indicated l8. The extreme and of the terminal wire is again doubled baclnand the several elements comprising the terminating assembly are then made secureby having wrapped over them, together with the remaining portion of the coil H, a sheathing material 23. The outer wrapper or sheathing 23 may be a fabric or other fibrous tightly drawn jacket. It serves both as an electrical insulation and as a binder. In the latter capacity, it not only secures the general class of coil convolutions l5 against lateral displacement. and unraveling, but also it compels the concluding turn or convolution to cleave to its subjacent and adjoining ones.

The extremity of lead wire I I is extended to the periphery of the coil by providing a small opening in the wrapper 23 or by leading the extremity of wire I! around the edge of the wrapper 23 and adjacent the spool flange H. A suitable adhesive which secures the wrapper material 23 in position serves also to anchor that portion of the wrapper 23 which covers the extremity of lead ll against casual effort at unraveling or unwinding.

While the present invention has been explained and described in contemplation of a specific embodiment as indicated by the accompanying drawing, and by the following specification, it is to be understood that numerous modifications and variations may be made without departing from the spirit of this invention. Accordingly, it is intended not to be limited by the specific language of the foregoing specification nor by the details of the accompanying drawing, except as indicated by the hereunto appended claims.

What is claimed is:

l. A method of forming and securing wire coils comprising the steps of winding a principal coil consisting of a plurality of layers of convolutions superimposed one upon another, emending the terminal of said wire through an eyelet opening of a lashing plate, reversing the direction of winding to eifect a reversed convolution, extending said lead through an opposite eyelet opening 5 of the lashing plate, continuing in the original direction of winding of the convolutions of said coil, and applying an enveloping sheathing onto the surface of said coil for binding together the outer layer of convolutions, said lashing plate, and said 10 reverse convolution.

2. An electric coil comprising a core, a spool associated with said. core, a plurality of helically wound coil convolutions of wire turned about said spool in layers superimposed one upon an- 15 other, and means for securing the convolutions of said coil against unwinding comprising a floating tie plate having endmost thereof a pair of oppositely disposed eyelets, a portion of said coil wire extended through one of said eyelets and m doubled back upon itself to comprise a reverse convolution to said plurality of helically wound convolutions, then extending through the other eyelet opening of said plate and being again reversed and continuing in the principal direction 95 of winding of said coil, and sheathing means for wrapping said endmost convolutions and plate frictionally into engagement with its nether convolutions.

WALTER H. PAGENKOPF. 

